Our shades are made of aluminum and are fixed to your barrel with Velcro (included) allowing them to be installed and removed easily. We don't recommend the use of these on blued surfaces as the adhesive on Velco could damage blueing if left on for a long time. Shades are 18 inches and 24 inches long and 2 inches wide. They can easily be cut to length as desired. Mainly used on benchrest or varmint rifles to redirect barrel heat from scope viewing area. The heat can cause a distortion of your scope image. Shades come with adhesive backed Velcro fasteners.